Some mobile phone devices can use wireless Internet connections, instead of a cellular network associated with the mobile phone devices, to access applications, such as Internet protocol (IP) multimedia subsystem (IMS) applications, of an operator of the cellular network. To access the applications of the operator, the mobile phone devices use the IP security (IPsec) tunneling protocol to establish a connection via an evolved packet data gateway (ePDG) of the cellular network. However, these mobile phone devices often establish the wireless Internet connection via firewalls that do not support the IPsec tunneling protocol. When that is the case, the mobile phone devices are unable to access the applications of the operator.